*{
    margin:0;
    padding:0;
}

.container{
    width:900px;
    height:600px;
    border:2px dashed #00f;
    /* position:relative; */
    margin:0 auto;
}

.wrap{
    width:500px;
    height:500px;
    border:1px solid #f00;
    padding:10px;
    margin:50px auto;
    position: relative;
}

.box{
    width:200px;
    height:200px;
    background:#00f;
    position:absolute;
}